2. Modelling Workstream ExternalWorkshop 2ndofMay FINAL · Aquaculture workshop 2 May 2019 31...

Aquaculture workshop2 May 2019

Aquaculture Modelling

Alan Hills & Andrew Berkeley1


Presentation Structure• Review Some Key Concepts

• Proposed New Modelling Workflow – What’s New?

• Introduce Screening Modelling

• Update on Depomod

• Marine Modelling/Bath Treatment Modelling

• Application Modelling Requirements

• Summary of Key Points

2


Key Concept – Mixing Zone

3

100 m RadiusMixing Zone ForMarine Outfalls

Chronic ImpactsAllowed Within

Mixing Zone


Key Concept – Mixing Zone - Aquaculture

4

100 m FromFarm Cage

Edge

Farm Cage

OverlappingAreas

Applies toSeabed

Ecology & InFeed

Chemicals


Key Concept – Mixing Zone - Aquaculture

5

EquivalentAreas

DEPOMOD


Key Concept – Wider Impacts

6

Mixing zone

MarineModelling


Key Concept – Marine Modelling

7

CreateMesh


Key Concept – Marine Modelling

8

RunModel

Aquaculture workshop2 May 2019 9


Proposed Modelling Workflow: What’s New (1)Present Approach New Approach

Minimal Pre-Application Discussion. Structured Pre-Application Discussion.

No Initial Screening of Impacts. Initial Screening Modelling To InformRisk Discussion.

No Agreed Method For AddressingRisks – Rely On Standard Method ForAll.

Agreed “Method Statement” To AddressRisks – Flexible and Risk Proportionate.

15 Days Of Current Meter Data – NotAlways Checked At Pre-App.

90 Days of Current Meter Data CheckedAt Pre-App - Required.


Proposed Modelling Workflow: What’s New (2)Present Approach New Approach

Local Impact Modelling With Old Model. Local Impact Modelling With New Model.

Simple Assessment OfSpatial/Cumulative Impact AndInteractions.

Marine Modelling To InformSpatial/Cumulative Impact AndInteractions.

Bath Treatment Modelling With OldSimplified Tools.

Bath Treatment Modelling with MarineModel.

Some Modelling/Data Issues OftenIdentified At Application Stage =Potential Delays.

Modelling/Data Issues Identified At Pre-App Stage.


Screening Modelling – Coverage – 2D Models



Pentland FirthOrkney Waters

Shetland (InDevelopment)



East CoastLewis & Harris

WiderLochLinnheSystem



Firth ofClyde

SouthernHebrides


Screening Modelling – Method – 2D Models• Indicative One Month Run Using Average:

• Tide• Wind• River Flow

• Particle Modelling (Sediment, In-Feeds).

• Dissolved Modelling (Bath, Nutrients).

• Can Include Inputs From MultipleSources.


Screening Modelling – Output – Current SpeedMeanCurrentSpeed(m/s)


Screening Modelling – Output – Particle Modelling


Screening Modelling – Advantages• Consistent Modelling Method.

• Informs Risk Discussion At An EarlyStage.

• Visualisation Of Potential Impacts Helpswith Discussions.

• Assists with Marine ModellingDevelopment.

• Method Can Be Improved and RefinedOver Time.

20

Local scale (“mixing zone”) modelling -NewDepomod

Calculatemixing zonearea

Predicted impactarea(NewDepomod)

Actualimpactproduced

Actualimpactmonitored

Actual impactareaestimated

Model indicates whether impact arealikely to exceed mixing zone area

Measured areamust not exceedmixing zone area

21

Why ellipses?• Need to produce area estimate from limited data – simplifying assumptions

required

• Dispersive processes acting equally in all directions expected to produce circularimpact

• In cases where bi-directional asymmetries occur this generalises to an ellipse

• Tidal currents described conceptually in terms of “tidal ellipses”

• Ellipse can be fitted to arbitrary numbers of sampling transects

22

NewDepomod AutoDepomod

Mean bedspeed 25 cm/s

Mean bedspeed 7 cm/s

Max, 340 ug/kg

Max, 20 ug/kg

Max, 0.45ug/kg

Max, 0 ug/kg

Max, 40 ug/kg

Max, 2.8 ug/kg

23

Modelled, 90,124 m2

Measured, 89,317 m2

• AutoDepomod used a single snapshot in time of deposition to identifyecological impacts

• This is not reliable given that deposition can vary on hourly timescales

• Most robust signal for predicting IQI impact area is based on a ve ra gedeposition rates through time


Local scale (“mixing zone”) modelling -NewDepomod

• Improves on AutoDepomod: predicts impacts in high-energy locations,distributes material more realistically in lower-energy areas

• Good for impact sca le , sometimes with positional errors

• Performance can be anchored and validated with good seabed data – thisshould become common practice for existing sites given future monitoringrequirements

• New methodological guidance issued shortly


Marine Modelling/Bath Treatment Modelling


Bath Treatment Modelling - Simple Approach


Marine Modelling/Bath Treatment Modelling• Single Dye Releases Challenging To

Model.

• Models May Be Used To Determine TotalArea of Potential Exposure.

• Smaller Scale Dye Releases Likely To BeRequired To Check Marine Model.

• Be Mindful of Lead Time For Dye ReleasePermission from Marine Scotland (10 To12 Weeks).


Modelling Requirements - Depomod• Depomod

• Driven By 90 Days Of Current Meter Data.• Default Risk Assessment Settings.• Can Be Compared Against Existing

Monitoring.• Modelling Checked At Pre-Application Stage.

• Key Outputs• Assess Likelihood of Mixing Zone

Compliance.• In-Feed Chemical Permit Limits.• Provides Baseline Survey Guide.

• Issue• Model performance issues in Complex Areas.

Technical Guidance andSubmission Guidance


Modelling Requirements – Marine Modelling• Marine Modelling

• More Detailed Version of ScreeningModelling.

• Generally Required For All Applications.

• Exceptions Possible For Low RiskProposals.

• Complexity Appropriate To Risk.

• Key Outputs• Cumulative Impact Information.

• Impact on Features of Interest.

• Bath Chemical Permit Limits.

Technical Guidance andSubmission Guidance


Summary Of Key Points – Modelling Process

ModellingProcess

ScreeningModelling WillImprove RiskDiscussion

More TechnicalWork At Pre-Application

Stage

Consistent WithApproach ToOther SEPA

Marine Permits

“MethodStatement” ForAgreeing Work

Should AddressAgreed Risks

Technical AndSubmission

Guidance WillBe Available


Summary Of Key Points – Screening Modelling

ScreeningModelling

Coverage AndMethod Can Be

Developed

Takes Accountof Impacts

From MultipleSources

Visualisation ofImpacts

Outside MixingZone

Will ImproveAquaculture

DecisionMaking

Can InformBaselineSurvey

May Be UsefulFor Non-

AquacultureMarine Issues


Summary Of Key Points - Depomod

Depomod

Model ImprovedAnd MoreFlexible

More RealisticGuide To

Mixing ZoneImpacts

Driven By 90Days Of Current

Meter Data

Can Be DrivenBy Marine

Model Output

Can InformBaselineSurvey

Performance InComplex Areas

Must BeTreated With

Caution


Summary Of Key Points – Marine Modelling

MarineModelling

More DetailedVersion OfScreeningModelling

CumulativeImpact

Information

ImpactInformation On

FeaturesOutside theMixing Zone

GenerallyRequired For

All Sites

MultipleSubstancesModelled,

Including Baths

BetterVisualisation

andQuantification

of Impacts

2. Modelling Workstream ExternalWorkshop 2ndofMay FINAL · Aquaculture workshop 2 May 2019 31...

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